1. Technical Field
The invention relates to a wiring substrate, and a method for manufacturing a wiring substrate, having a pad covered with a metal film.
2. Description of the Related Art
A pad of a wiring substrate is generally covered with a two-layered Ni/Au plating film for improving connection reliability. The Ni/Au plating film is formed using electrolytic plating in place of electroless plating, in many cases, from an economic point of view. Lead patterns are connected to respective bonding pads so that the pads can be electrically connected to a power supply outside of the wiring substrate for the electrolytic plating process. Portions of the lead patterns are also covered with the Ni/Au film by the plating process. After the plating process, portions of the lead patterns are removed in a removal process to provide the bonding pad. Japanese Patent Application Publication (JP-B) No. 63-18355, for example, discloses a method for removing a lead pattern. The method of JP-B-63-18355 discloses covering a bonding pad with a Ni/Au plating film, using the Ni/Au plating film as an etching resist, and removing a portion of the lead pattern not covered with the Ni/Au plating film by etching. The contents of JP-B-63-18355 are incorporated herein by reference in their entirety.